Fluid amplifier with automatic reset of the power stream



Feb. 25, 1964 E. u. SOWERS m 3,122,039

FLUID AMPLIFIER WITH AUTOMATIC RESET OF THE POWERSTREAM Filed Feb. 16, 1962 2 Sheets-Sheet 1 FIG lb H6. /0

I0 I l4 l0 & 2 4 HH n I3 n 5 l6 TRANSDUCER I INVENTOR [flI/IV 1/. MIT/75E ATTORNEY 5 Feb. 25, 1964 Filed Feb. 16, I962 E. U. SOWERS ll] FLUID AMPLIFIER WITH AUTOMATIC RESET OF THE POWER STREAM 2 Sheets-Sheet 2 Fla. 2 Fla. 5 F/a 4 so 49 H6. 5

: t 1 TO OTHER D l 51 TRANSDUCERS A 4 W 56 l, 57 E TRANSDUCER 1:111: 4 J 1 1 55 1'2 TRANSLATER 54 United States Patent 3 122 039 FLUID AMPMFHER WiTH AUTOMATIC RESET OF THE PUWER STREAM Edwin U. Sewers ill, Philadelphia, Pa., assignor to Sperry Rand Corporation, New York, N.Y., a corporation of Delaware Fiied Feb. 16, 1962, Ser. No. 173,677 15 tCiairns. (Cl. 83-71) This invention generally relates to apparatus for convetting a fluid energy pulse into a mechanical energy pulse, which finds particular utility in magnetic tapeto-card punch devices and the like.

Prior art devices for transferring information between different kinds of storage mediums, for example, from magnetic tape to punched card records, normally employ means to scan the magnetic record in order to generate an electrical pulse for each magnetized bit thereon. This pulse in turn operates an electro-magnet for driving the punch body through the record card. In other types of information transferring devices, the electrical pulses generated by information stored on one carrier may be used to actuate typewriter linkages for imprinting characters on a carrier member, or may be used in printers wherein a print hammer is actuated to force a carrier member against the faces of type mounted on a rotating wheel or the like. In all of these prior art converters, the actuating power for the driven mechanical element is provided directly by amplified electrical signals, or indirectly by a linkage giving a mechanical advantage, said linkage in turn being operated by electrical power.

The present invention provides a new and novel converter in which the driven mechanical element, such as a print hammer or a punch body, is directly powered by fluid energy. When employing the invention in a tapeto-card environment or in any analogous environment where information is extracted from a storage medium in the form of electrical pulses, a transducer is provided to change this electrical pulse energy into fluid pulse energy which in turn provides the driving force of the mechanical body.

It is thus an object of the present invention to provide apparatus for converting fluid pulse energy into mechanical energy where the latter is exhibited by the motion of a mechanical body.

Another object of the present invention is to provide means whereby electrical pulse energy is ultimately converted into mechanical energy by the intermediate use of fluid pulse energy.

One of the novel features of the present invention is the provision of a pure fluid amplifier of the boundary layer type whose power jet stream acts as the prime motive force on the mechanical body. There is further provided automatic reset of the power stream to a stable quiescent condition after said body is driven to perform work whether it be of punching, printing, impact or the like. In a boundary layer fluid amplifier, a high energy power jet isdirected toward a target area or a receiving aperture system by the pressure distribution in the power jet boundary layer region. This pressure distribution is controlled by the wall configuration of the interaction chamber, the power jet energy level, the fluid transport characteristics, the backloading of the amplifier output passages, and the flow of control fluid to the power jet boundary layer region. In this type of fluid amplifier, special design of the interaction chamber configuration permits the power jet to lock on to one side wall and remain in said locked on flow configuration without flow of a control fluid. Thus, when the power jet is suitably deflected by a control fluid flow, it looks onto the side Wall of an output channel to which it is diverted and remains therein even after the control fluid flow ceases.

Such a pure fluid amplifier thereby possesses positive feedback since the feedback path is created and destroyed each time that the power jet is deflected to another output channel.

In the present invention, this boundary layer phenomenon is employed to maintain the power stream in an output channel to thereby force the mechanical body to its work station. After the work has been performed, the pressure in the output channel builds up to such a value that the power stream is diverted away from entering the channel, and the body is enabled to return to its stable quiescent station. Thus, only one control input need be provided to initially force the power stream into this output channel wherein the pressure there created causes the mechanical body to perform work. The power stream remains in this output channel only until said work is performed by the body, after which the pressure attained in said channel automatically forces the power stream to deflect into an exhaust channel without need for providing a separate reset control.

It is accordingly a further object of the present invention to provide a converter employing the characteristics of a boundary layer fluid amplifier wherein an output channel containing a movable mechanical body is designed to provide automatic reset of the power stream after work is performed by said body.

Yet another object of the present invention is to provide a converter of the type described above wherein the duration of power stream flow into an output channel is determined by the pressure value in said channel so that automatic reset of the power stream is effected subsequent to the performance of mechanical work.

Although the present invention is shown and described in the environment of recorders and the like, it has utility wherever an impact mechanical force is desired.

These and other objects of the present invention will become apparent during the course of the following description which is to be read in conjunction with the drawings, in which:

FIGURES 1a and 1b are views partially in section of one embodiment of the invention for converting signals read from a magnetic tape or the like into motion of a punch body for perforating a record card;

FIGURE 2 is a view in section of one kind of electric pulse-to-fluid pulse transducer which may be used in the embodiment of FIGURE 1a;

FIGURE 3 is another form of transducer which may be used in FIGURE 1a; 7

FIGURE 4 is a partial view in section of an alternative embodiment similar to FIGURE 1 but where a print hammer is actuated by a fluid pulse; and

FIGURE 5 is a third possible embodiment of the present invention shown in diagrammatic form wherein a typewriter linkage may be actuated by the fluid pulse.

Referring first to FIGURES 1a and lb, reference numeral ll indicates a record card which is to be perforated each time that a magnetized area on magnetic tape 11 passes beneath a read head 12. A punch body 13 sharpened at end 14 is inserted Within a recess 15 in body 16. Coiled about punch body 13 is a helical spring 17 which bears against a flange 13 at the other end of punch body 13 in order to maintain said punch body in its retracted position in the absence of an actuating fluid pulse. Flange 18 is shown to be closely fitted within recess 15 in order to effectively seal the volume occupied by spring 17 from the volume created below flange 18 when punch body 13 extends outwardly of body 16 and through record card 10.

Connected with recess 15 is a channel 19 which is one output channel of a pure fluid amplifier generally comprised of the interconnected fluid ducts enclosed by dotdash rectangle 20 in body 16. This pure fluid amplifier consists of an input power stream channel 21 which is provided with either a liquid or gaseous fluid from a pump or compressor, not shown in any of the figures. The fluid under pressure in power stream channel 21 issues into an interaction chamber 22 via a power orifice 23. Chamber 22 is bounded by the two outer converging walls 26 and 27 of output channels 19 and 24, whose inner converging walls intersect to form a dividing knife edge 25. The outer walls 26 and 27 of the output channels may also undergo an acute change of slope to form cavi ties 28 and 29, respectively, in order to insure that the power stream will be maintained in the output channel to which it is diverted unless the pressure in said output channel rises above a certain threshold value. Such an increase in pressure in output channel 19 through which the power stream is flowing may be caused by backloading in the manner subsequently to be described. Output channel 19 feeds into recess 17 as previously mentioned, while output channel 24 may be returned to the inlet of the power stream source through an exit port 36 in body 16.

It will be noted in FIGURE 1a that the walls 26 and 27 of chamber 22 are oflset with respect to power orifice 23. This offset configuration, coupled with the cavities 28 and 29 in the respective output channels, allows the power stream to maintain its flow through whichever one of output channels it is diverted. This memory phenomenon is exhibited because of creation of the so-called boundary layer region, which is a low pressure region between the power stream and the wall of the output channel through which said stream passes. Creation of a boundary layer region in fluid amplifiers, to provide positive feedback and thus a self-locking feature, is per se old. However, the provision of cavities is not absolutely essential since the ollset region near the nozzle 23 exit and/ or suitably curved walls 26 and 27 may be suflicient to maintain boundary layer lockon.

In the quiescent condition of the device shown in FIG- URES 1a and 1b, the power stream issuing from orifice 23 flows through output channel 24 and exhausts via port 30. This is a stable condition since creation of a boundary layer region between the power stream and the outer wall 27 of channel 24 provides a positive feedback action to thereby lock the power stream onto this wall of the channel, where it will be maintained until some condition arises to divert the power stream away from entering channel 24 and into channel 19. The condition under which the power stream is thus diverted from channel 24 to channel 19 will be described in later paragraphs. For the present it is sufficient to say that such switching of the power stream occurs whenever it is desired to punch a hole in record card 16. While the power stream is flowing through output channel 24, a certain quiescent pressure exists in output channel 19 as determined by the pressure of the power stream as it flows through chamber 22 on its way to output channel 24. This quiescent pressure in output channel 19 is slightly less than atmospheric, so that in the absence of power stream flow through output channel 19, the movable mechanical body 13 is stationary.

Upon the power stream being diverted or shifted into output channel 19, its fluid particles enter the channel with velocity and pressure so as to apply an upward force against the flange end 18 of body 13. As before mentioned, flange 1% is preferably fitted within recess to prevent any substantial amount of fluid in channel 19 from flowing into the outside environment. Actually, the power stream makes a U turn at the blocked outlet of channel 19 and eventually exits through channel 24 to port 39. The factors involved in this phenomenon are the location of cavity 23, its geometry, and the width of channel 19. However, inasmuch as the exhaust aperture from channel 19 is considerably reduced, if not completely blocked, the number of fluid particles in channel 19 begins to increase with a consequent increase in pressure in that channel. This pressure eventually reaches a designed first threshold value such that the force now applied against flange end 18 exceeds the force applied by restraining means 17 and the external atmospheric pressure. Consequently, an unbalanced force is now applied in a direction to drive punch body 13 through record card 1% in the manner indicated by FIGURE 111. As the punch body is thus driven upwards, flange end 18 moves to effectively increase the volume of channel 19 which may be occupied by the fluid particles. However, this slight increase in the volume of channel 19 does not substantially reduce the backloading of the channel, so that the pressure still continues to thereafter increase as more and more of the power stream particles occupy this enlarged volume.

The configuration of channel 19, especially in the region of cavity 23, is so designed that upon a certain second threshold value of pressure being attained therein (subsequent to attainment of the first threshold value), the power stream no longer maintains its flow in output channel 19 but instead is diverted back into output channel 24. This designed second threshold value also depends upon the wall configuration of chamber 22, as well as on the power jet energy level, the degree of backloading of the output channel 19 (i.e., degree of obstruction of said channel by flange l3), and other variables which are well known to those skilled in the art. The presence of the cavity 28 may be desirable, but not necessary, since it causes generation of a vortex within the channel as the power stream flows therethrough which aids in creating the boundary layer region essential to the positive self-locking efl'ect. Thus, by modifying or even eliminating said cavity, the power stream can be made to switch from channel 19 back to channel 24 for a wide range of channel pressures. However, the second threshold value of pressure must be higher than the first threshold value required to drive the punch body upward through the record card, so that this mechanical motion occurs before the power stream is diverted away from entering channel 19.

Upon the power stream being diverted back into channel 2 5, the excess fluid in channel 19 exhausts back into interaction chamber 22 so that the pressure in channel 1% returns to its quiescent value. By such action, the punch body 13 is returned to its retracted position due to the force exerted by the reset spring 17.

The means employed in the preferred embodiment of the invention, whereby the power stream is shifted from output channel 24 to output channel 19, is a control stream orifice 31 located in side wall 27 of chamber 22. Associated with this control orifice is a control stream channel 32 in body is through which is applied a fluid pressure pulse. This pressure pulse in control channel 32 is created by a transducer of some type generally indicated by block 33 in FIGURE 1a, which is connected to control channel 32 via a conduit 34. If the power stream issuing into chamber 22 is locked on to wall 27 so as to flow through output channel 2 a sufiicient increase in pressure at control orifice 31 will break the boundary layer region created adjacent said wall so as to make unstable said power stream flow. In this case, the power stream switches to change direction so that it is now diverted into output channel 1'19. Upon being diverted to channel 19, a boundary layer region is thereby created adjacent wall 26 to thereafter maintain power stream flow therein even after termination of the pressure pulse at control orifice 31. The only way in which the power stream can now be diverted back into output channel 24 is by the subsequent increase in pressure in channel 119 to the designed second threshold value. This in turn makes power stream flow in channel 19 unstable so as to divert it back into output channel 24. Upon completion of this cycle, a boundary layer region is again created between the power stream and Wall 27 to cause said power stream to lock on and thus maintain its flow in channel 24 until the appearance of another pressure pulse at control orifice 31.

As before mentioned, one useful function of this invention is to provide means whereby an electrical pulse induced in the winding of head 12 is converted into a perforation in record card 10. Said electrical pulse may be directed to transducer 33 Via amplifier 35 in order to convert the electrical energy into a pressure pulse in channel 32. Although many different kinds of transducers can be employed, two diverse types are shown in FIGURE 2 and FIGURE 3. In FIGURE 2, a pair of piezo-electric crystals 38 and 39 are located on opposite sides of a fluid channel 40 such that they normally extend into said channel in order to block flow of fluid therein. Here, fluid from a pressure source (not shown) enters the transducer via an inlet port 41 and attempts to flow through channel 4% into output conduit 34. However, in the absence of an electrical potential across conductors 36 and 37, the piezo-electric crystals 38 and 35 extend inwardly of channel 40 in order to block any substantial flow of fluid therethrough, so that the pressure existing to the right of these crystals is not suilicient to disrupt the boundary layer region adjacent wall 27 in which orifice 31 is located. Upon an electrical signal of proper polarity being applied across conductors 36 and 37 (which in FIGURE 1a is generated by the passage of a magnetized area beneath read head 12), a compression stress is exerted along the mechanical axes of crystals 38 and 39 of sui'ficient magnitude to cause retraction of said crystals from the channel 40 so as to permit passage of fluid therethrough. Thus, the electrical signal applied between conductors 36 and 37 opens the valve in channel 40 to permit the fluid from inlet port 41 to flow via conduit 34 and channel 32 into chamber 22. This fluid control stream issuing from orifice 31 is suflicient to disperse the boundary layer region and so divert the power stream into output channel 19. When the electrical signal disappears from conductors 36 and 37, crystals 33 and 39 again return to their extended position to effectively block fluid flow in channel 40 and thus terminate the control stream from orifice 31. By this time, however, the power stream is flowing through output channel 19 and will be maintained therein by the creation of a boundary layer region until the Second threshold value of pressure is attained in this output channel. The time required for this second threshold value of pressure to be reached, when once the power stream begins to flow in channel 19, should be less than the time interval between the sensing of adjacent magnetic marks on member 11, so that the power stream switches back to its initial condition through output channel 24 before occurrence of another control stream pulse from orifice 31.

FIGURE 3 shows an alternative transducer which may be employed in the present invention. In this transducer, the details of which are more fully disclosed in pending application Serial No. 89,863, filed by Cargill et al. on February 16, 1961, a flexible diaphragm 42 is fixed in a channel 43 to which is connected the conduit 34 shown in FIGURE 1. Channel 43, conduit 34, and channel 32 are filled with fluid which may be the same as the fluid comprising the power stream in fluid amplifier 20. In order to vibrate diaphragm 42 and thus set up pressure waves in the fluid, a voice coil 44 or the like may be provided to which are attached conductors 36 and 3'7. When read head 12 senses the passage of a magnetic mark therebeneath, an electrical pulse on conductors 36 and 37 causes diaphragm 42 to vibrate, thus setting up compression waves in the fluid of channel 32. The increase in pressure, due to the compression wave in the fluid, appears at orifice 31 and is effective to break the boundary layer region adjacent Wall 27 so as to divert the power stream into output channel 19.

Besides the piezoelectric and magnetic transducers shown in FIGURES 2 and 3, other types may be employed such as a movable plate capacitor or the like. All that is required to divert the power stream into output channel 19 is a temporary pressure pulse at orifice 31 suflicient in magnitude to destroy the boundary layer region which normally maintains power stream flow through channel 24. The divider edge 25 in chamber 22 may be offset with respect to the longitudinal axis of orifice 23 so that the entrance to channel 24 is larger than the entrance to channel 19. This insures that the power stream initially flows through exhaust channel 24 rather than through channel 19 at the time when the power stream source is initially connected to channel 21. FIGURES 4 and 5 illustrate how the piston member 13 can be made to perform work other than perforating record cards. For example, in FIGURE 4 a body 45 is employed as a print hammer for driving a paper web 46 or the like against the face of a type character 47 located on a type wheel 48. Thus, the movable piston 45, which is similar in construction to piston 13 in FIGURE la, is employed to provide an impact force for imprinting the impression of a type face of a typical rotating wheel printer. In FIGURE 5, there is shown how a typewriter linkage 49 can be actuated by a piston member 5% which is driven by the build-up in pressure in an output channel 51 corresponding to output channel I9 in FIGURE la. Piston St) is fitted within channel 51 so that it is driven outward when the first threshold pressure is attained. FIGURE 5 further illustrates how a typical record card, having a plurality of columns in which characters are represented by a four bit binary code, may be scanned by brushes 53 so that a translator 54 selects an output line 55 to energize an associated transducer 56 which in turn causes piston Stl to actuate a typewriter linkage and print a particular character. Thus, the present invention will find extensive use in the recording art or the like since it provides pure fluid actuation of the recording mechanism together with automatic reset to a quiescent stable condition. The invention will also find use in other environments where an impact force is required.

Although the embodiments disclosed herein include the conversion of electrical energy to fluid pulse energy, the present invention is not so restricted, since the control stream pulse issuing ifrom orifice 31 can be initiated by other means. Furthermore, other methods may be employed to temporarily divert the power stream into channel 1?. In essence, therefore, the basic concept of this invention is the arrangement of a movable body positioned to backload one output channel of a fluid amplifier of the boundary layer type so that motion of the body occurs prior to the attaining of a switch back pressure in said channel. It should further be stated that the means for resetting the movable body in its quiescent position may either be additional means, such as the coil spring I7 shown in FIGURE la, or it might be the weight of piston 13 itself. Therefore, it is apparent that many modifications may be made to the preferred embodiments by one skilled in the art without departing i rom the spirit of the invention as defined in the appended claims.

I claim:

1. Apparatus for converting fluid pressure aulse energy hrto mechanical pulse energy, which comprises:

(a) a fluid amplifier of the boundary layer type wherein the fluid power jet stream locks onto a wall of an output channel, to which it is diverted, for any pressure in said output channel less than a second threshold value;

(b) means located within said output channel and movable from a first position towards a second position for increasing the volume of said output channel when the pressure therein is greater than a first threshold value, where said first threshold value is less than said second threshold value; and

(0) means for diverting said power stream into said output channel, whereupon the pressure in said output channel subsequently increases from a quiescent value lower than said first threshold value to said second threshold value which in turn divents said power stream away from entering said output channel.

2. Apparatus according to claim 1 wherein said power stream diverting means comprises means for generating a fluid control jet stream pulse which impinges upon said power stream to divert the latter into said output channel.

3. Apparatus according to claim 1 wherein said power stream divesting means comprises transducer means responsive to an electrical pulse for generating a fluid control jet stream pulse which impinges upon said power stream to divert the latter into said output channel.

4. App-Ara us according to claim 1 wherein said movable means is a piston member fitted within said output channel.

5. Apparatus according to calm 1 wherein said power stream diverting means is responsive to an electrical signal.

6. Apparatus for converting fluid pressure pulse energy into mechanical pulse energy; which comprises:

(a) a fluid amplifier or" the boundary layer type Wherein the fiuid power jet stream locks onto a wall of an output channel, to which it is diverted, for any pressure in said output channel less than a second threshold value;

(b) means located within said output channel and movable from a first position towards a second position for increasing the volume of said output channel;

() means resetting said movable means at said first position for any pressure in said output channel less than a first threshold value, where said first threshold value is less than said second threshold value; and

(d) means for diverting said power stream into said output channel, whereupon the pressure in said output channel subsequently increases from a quiescent value lower than said first threshold value to said second threshold varue which in turn diverts said power stream away from entering said output channel.

7. Apparatus according to claim 6 wherein said power stream diverting means compni-ses means for generating a fluid control jet stream pulse which impinges upon said power stream :to divert the latter into said output channel.

8. Apparatus according to claim 6 wherein said movable means is a punch body.

9. Apparatus according to claim 6 wherein said movable means is a print hammer.

14 Ap aratus according to claim 6 wherein said resetting means is a spring member applying force against said movable means in a direction opposite to the force applied by the pressure in said output channel.

11. Apparatus according to claim 6 wherein said power stream diverting means is responsive to an electrical signal.

12. Apparatus for converting fluid pressure pulse energy into mechanical energy which comprises:

(a) a fluid chamber;

(b) a power orifice in one wall of said chamber which is adapted to supply a fluid power jet stream into said chamber;

(0) first and second output channels branching from said chamber into either of which said power stream can be diverted, where power stream flow through said first output channel is stable and said second output channel is designed to enable said power stream to maintain its fiow therethrough by boundry layer lockon for any pressure therein which is less than a second threshold value;

((1) means located within said second output channel and movable from a first position towards a second position for increasing the volume of said second output channel when the p "esstue therein is greater than a first threshold value, where said first threshold value is less than said second threshold value; and

(e) means for diver ing said power stream from said first output channel into said second output channel, whereupon the pressure in said second output channel subsequently increases from a quiescent value lower than said first threshold value to said second threshold value which in turn diverts said power stream away from entering said second output channel and back into said first output channel.

13. Apparatus according to claim 12 wherein said power stream diver ing means comprises a control orifice in one wall of said chamber, and means adapted to supply a fiuid control jet stream pulse into said chamber via said control orifice which impinges upon said power stream to divert the latter into said second output channel.

14. Apparatus according to claim 12 wherein said power stream diverting means is responsive to an electrical signal.

15. Apparatus according to claim 12 wherein is further included means resetting said movable means at said first position for any pressure in said output channel less than said first threshold value.

References Ci ed in the file of this patent UNITED STATES PATENTS 

1. APPARATUS FOR CONVERTING FLUID PRESSURE PULSE ENERGY INTO MECHANICAL PULSE ENERGY, WHICH COMPRISES: (A) A FLUID AMPLIFIER OF THE BOUNDARY LAYER TYPE WHEREIN THE FLUID POWER JET STREAM LOCKS ONTO A WALL OF AN OUTPUT CHANNEL, TO WHICH IT IS DIVERTED, FOR ANY PRESSURE IN SAID OUTPUT CHANNEL LESS THAN A SECOND THRESHOLD VALUE; (B) MEANS LOCATED WITHIN SAID OUTPUT CHANNEL AND MOVABLE FROM A FIRST POSITION TOWARDS A SECOND POSITION FOR INCREASING THE VOLUME OF SAID OUTPUT CHANNEL WHEN THE PRESSURE THEREIN IS GREATER THAN A FIRST THRESHOLD VALUE, WHERE SAID FIRST THRESHOLD VALUE IS LESS THAN SAID SECOND THRESHOLD VALUE; AND (C) MEANS FOR DIVERTING SAID POWER STREAM INTO SAID OUTPUT CHANNEL, WHEREUPON THE PRESSURE IN SAID OUTPUT CHANNEL SUBSEQUENTLY INCREASES FROM A QUIESCENT VALUE LOWER THAN SAID FIRST THRESHOLD VALUE TO SAID SECOND THRESHOLD VALUE WHICH IN TURN DIVERTS SAID POWER STREAM AWAY FROM ENTERING SAID OUTPUT CHANNEL. 